IDENTIFICATION OF POTENTIAL HOST OF Cowpea aphid-borne mosaic virus

The yellow passion fruit (Passiflora edulis) belongs to the order Passiflorales and genus Passiflora, is a plant adapted to tropical climates and that from 1970 gained featured in the national scenario. However, the culture can be affected by the Cowpea aphid-borne mosaic virus (CABMV), responsible for causing the passion fruit woodiness, considered to be one of the main responsible for loss of productivity of the crop. Some characteristic symptoms of virus infection include mosaic, blisters and leaf deformations, and fruit woodness. Great concern about this disease is around weeds found in passion fruit orchards, which can serve as alternative hosts of the virus, and inoculum source in the fallow period. The objective of the present work was to identify potential host plants of CABMV. The experiment was conducted at the Experimental Station of IAPAR Londrina, PR, with three replications. The specie Crotalaria spectabilis was selected to evaluate the host potential of the virus. The seeds of this plant were germinated in gerbox with sand in a greenhouse, until reaching approximately 0.1 m of length, and then transplanted to a pot containing substrate. In order to perform the biological indexing of this material, after four days of transplanting, the plants were mechanically inoculated using as inoculum source yellow passion fruit plants contaminated with CABMV from the city of Londrina-PR. Evaluations of symptoms and collections of plant material occurred 4, 9 and 14 days after inoculation with the virus. From the collected material, the total RNA was extracted using Trizol® Reagent (Invitrogen), according to the manufacturer's instructions. Molecular detection was done by means of RT-PCR (Reverse Transcription Polymerase Chain Reaction) using the CABMV-Forward and CABMV-Reverse specific oligonucleotides. The RT-PCR product was stained with Sybr Gold® (Invitrogen) and electrophoretically separated on 1% agarose gel using as standard the 1kb DNA Ladder Plus marker. C. spactabilis was positive for CABMV in the biological indexing, being possible to observe characteristic symptoms of the virus infection. In RT-PCR the samples were positive, with amplification of 221 base pairs. Thus, it can be affirm that C. spectabilis acts as an alternative host of the CABMV virus under field conditions.